2002 dodge with Obd2 code P0122

I have a 2002 3500 with a HO 24 valve cummins. The engine cuts out between 1500 and 2000 rpm, the injector pump has about 8000 miles on it. It almost acts like there is a throttle position sensor out, but I don't believe it has one. Also when the injector pump went out the first time it was when I added some Lucas injector cleaner to my tank. I didn't think anything of it but I just added some more on the last tank full. This problem happened all of the sudden and I don't think the problem is related to the Lucas. The computer is throwing a code of P0122 which is a throttle position sensor Low input, I don't know what would cause it though... any help would be appreciated

Check your PM's

The throttle position sensor should be under that funky plastic cover on the driver's side of the engine, above the VP44, and ahead of the air intake pipe into the manifold.

When the pump went out last time did you have the lift pump checked? It might not be suppling enought fuel to the injection pump and the only diesels that I know of that have a tps are the fly by wire systems and those are on the peddel but it is posible that it has one if it dose it is going to be near the throdel linchage